Abstract: The present invention relates to a drilling device. The device comprises at least one drill rod, the or each drill rod having a first cylindrical wall defining an elongate chamber for receiving a working fluid to form a fluid column, the length of the fluid column being equal to a total length of the elongate chambers of the or each drill rod. The device also comprises a displacement excitation device arranged at a proximal end of the fluid column and configured to excite the fluid column to cause the working fluid in the fluid column to oscillate, wherein the excitation device is configured to excite the fluid column at an excitation frequency at or within 10% of a natural frequency of the fluid column determined based on the fluid column having a fixed boundary condition at a proximal end thereof.

Abstract: The present invention relates to a flapper valve for a percussion drill tool. The valve comprises a first side engageable with a planar surface of an element of the percussion drill tool to alternately close first and second fluid flow paths of the percussion drill tool. The planar surface comprises first and second apertures in fluid communication with the first and second fluid flow paths, respectively. The first side of the flapper valve comprises a first planar portion and a second planar portion and a first curved tip portion intermediate the first and second planar portions. The flapper valve is pivotable about the first curved tip portion between a first position, in which the first planar portion of the flapper valve is in sealing contact with the planar surface to close the first aperture, and a second position, in which the second planar portion of the flapper valve is in sealing contact with the planar surface to close the second aperture.

Abstract: The present invention relates to a drill bit assembly for fluid-operated percussion drill tools comprising a percussion bit having a head portion and a bit retaining portion. Engagement means are provided on the head portion engageable with complementary engagement means on a drive ring whereby rotational drive from the drive ring may be transmitted to the percussion bit. The assembly also comprises bit retaining means adapted for engagement with the bit retaining portion of the percussion bit to retain the percussion bit in the drill bit assembly. Connection means on the drive ring are adapted for connecting the drive ring to a drive means of the fluid-operated percussion drill tool. According to a first aspect, the drive ring comprises a plurality of separable part-annular drive dog segments, wherein the bit retaining means are provided on at least two of the drive dog segments.

Abstract: The present invention relates to a hydraulic down-the-hole hammer. The hammer comprises an elongate shaft and a piston having a central bore therethrough, the piston slidably mounted for reciprocal movement on the shaft and arranged to impact a percussion bit. Forward and rear drive chambers for the piston are disposed between the piston and the shaft and the forward chamber is separated from the rear chamber by an annular shoulder formed internally of the piston bore. The hammer also comprises a control valve to control reciprocation of the piston, wherein the control valve is arranged within the central bore of the piston. The hammer may be a disposable water hammer in which the piston is an outermost component of the hammer.

Abstract: A hydraulic percussion device comprising a piston mounted for reciprocal motion within a cylinder to impact a percussion bit and a control valve to control reciprocation of the piston. A valve pilot line is arranged to switch the control valve based on the position of the piston within the cylinder, wherein the valve pilot line is alternately connected, by the reciprocal movement of the piston, to high and low pressure lines (P, T) via an undercut in the piston. The undercut is located at a portion of the piston having a diameter less than the maximum sealing diameter of the piston.

Abstract: The present invention relates to a fluid-operated percussion drill tool comprising an outer wear sleeve comprising a substantially cylindrical wall and having inner and outer surfaces. The tool also comprises a percussion bit having a head portion and a bit retaining portion and located at a forward end of the outer wear sleeve. The tool further comprises a sliding piston mounted for reciprocating movement within the outer wear sleeve to strike the percussion bit. The tool also includes a drive ring having a substantially cylindrical wall and comprising connection means adapted for connecting the drive ring to a drive means of the fluid-operated percussion drill tool. At least one flushing channel provides a fluid path to the cutting face of the bit for a flushing medium.

Abstract: The present invention relates to a drill bit assembly for fluid-operated percussion drill tools. The drill bit assembly comprises a percussion bit having a head portion formed with an axially extending shank, a first plurality of axially extending splines on the shank slideably engageable with a first plurality of complementary splines formed internally of a drive chuck whereby rotational drive from the chuck may be transmitted to the shank. The assembly also comprises engagement means on the chuck adapted for connecting the chuck to a drive means of the fluid-operated percussion drill tool. During drilling, the bit and the chuck are held in a first relative orientation in which the bit is retained in the chuck, and the bit is moveable axially relative to the chuck to a bit removal position, in which the bit is rotatable relative to the chuck to a second relative orientation in which the bit is removable from the chuck.

Abstract: The present invention relates to a hydraulic down-the-hole hammer. The hammer comprises an elongate shaft and a piston having a central bore therethrough, the piston slidably mounted for reciprocal movement on the shaft and arranged to impact a percussion bit. Forward and rear drive chambers for the piston are disposed between the piston and the shaft and the forward chamber is separated from the rear chamber by an annular shoulder formed internally of the piston bore. The hammer also comprises a control valve to control reciprocation of the piston, wherein the control valve is arranged within the central bore of the piston. The hammer may be a disposable water hammer in which the piston is an outermost component of the hammer.

Abstract: The present invention relates to a drill bit assembly for fluid-operated percussion drill tools comprising a percussion bit having a head portion and a bit retaining portion. Engagement means are provided on the head portion engageable with complementary engagement means on a drive ring whereby rotational drive from the drive ring may be transmitted to the percussion bit. The assembly also comprises bit retaining means adapted for engagement with the bit retaining portion of the percussion bit to retain the percussion bit in the drill bit assembly. Connection means on the drive ring are adapted for connecting the drive ring to a drive means of the fluid-operated percussion drill tool. According to a first aspect, the drive ring comprises a plurality of separable part-annular drive dog segments, wherein the bit retaining means are provided on at least two of the drive dog segments.

Abstract: A drill bit assembly for fluid-operated percussion drill tools. The assembly comprises a percussion bit comprising a bit head detachably connected to an axially extending shank and engagement means formed on an external wall of the shank engageable with complementary engagement means formed internally of a drive chuck whereby rotational drive from the chuck may be transmitted to the shank. At least one flushing channel extends between the external wall of the bit shank and a cutting face of the bit head, to provide a fluid path for a flushing medium between the external wall of the bit shank and the cutting face of the bit head.

Abstract: A multi-indenter drill bit includes a plurality of indenters arranged on a drilling surface of a bit face. The ratio of the total indenter area to the bit face area is defined by a parameter KPI1 (expressed as a percentage), and the ratio of the average individual indenter area to the bit face area is defined by a parameter KPI2, (expressed as a percentage). The relationship between KPI1 and KPI2 is defined by an equation.

Abstract: The present invention relates to a hydraulically powered percussion mechanism (12), comprising a piston (6) to impact a percussion bit (8). The percussion mechanism also includes a first accumulator assembly (3a) for hydraulic fluid. The first accumulator assembly comprises a plurality of first accumulator elements (27). In a first aspect, the plurality of first accumulator elements are arranged in a common housing (14). In a second aspect, each of the first accumulator elements is arranged at the same proximity to the piston. In a third aspect, each of the first accumulator elements comprises an accumulator membrane (32) or piston, and wherein the primary direction of movement of the membrane or piston in contact with the hydraulic fluid is substantially parallel to a longitudinal axis of the mechanism.

Abstract: A drill bit assembly for fluid-operated percussion drill tools. The assembly comprises a percussion bit comprising a bit head detachably connected to an axially extending shank and engagement means formed on an external wall of the shank engageable with complementary engagement means formed internally of a drive chuck whereby rotational drive from the chuck may be transmitted to the shank. At least one flushing channel extends between the external wall of the bit shank and a cutting face of the bit head, to provide a fluid path for a flushing medium between the external wall of the bit shank and the cutting face of the bit head.

Abstract: A hydraulic percussion device comprising a piston mounted for reciprocal motion within a cylinder to impact a percussion bit and a control valve to control reciprocation of the piston. A valve pilot line is arranged to switch the control valve based on the position of the piston within the cylinder, wherein the valve pilot line is alternately connected, by the reciprocal movement of the piston, to high and low pressure lines (P, T) via an undercut in the piston. The undercut is located at a portion of the piston having a diameter less than the maximum sealing diameter of the piston.

Abstract: A multi-indenter drill bit comprising a plurality of indenters arranged on a drilling surface of a bit face, the ratio of the total indenter area to the bit face area being defined by a parameter KPI1 (expressed as a percentage); the ratio of the average individual indenter area to the bit face area being defined by a parameter KPI2, (expressed as a percentage) and wherein the relationship between KPI1 and KPI2 is defined by an equation.

Abstract: According to an aspect of the present invention, there is provided a release assembly (100) disposable axially between two components (A, B) of a percussion drill tool (10), wherein the components (A, B) are connectable together by means of a screw-threaded connection (20). The release assembly (100) comprises a release ring (102), the release ring (102) being tapered on at least a first side (103) in a first radial direction. The release assembly (100) also comprises a first counter element (105) arranged axially adjacent the first side (103) of the release ring (102), the first counter element (105) having a tapered side (106) for engagement with the first side (103) of the release ring (102).

Abstract: The present invention relates to a hydraulically powered percussion mechanism (12), comprising a piston (6) to impact a percussion bit (8). The percussion mechanism also includes a first accumulator assembly (3a) for hydraulic fluid. The first accumulator assembly comprises a plurality of first accumulator elements (27). In a first aspect, the plurality of first accumulator elements are arranged in a common housing (14). In a second aspect, each of the first accumulator elements is arranged at the same proximity to the piston. In a third aspect, each of the first accumulator elements comprises an accumulator membrane (32) or piston, and wherein the primary direction of movement of the membrane or piston in contact with the hydraulic fluid is substantially parallel to a longitudinal axis of the mechanism.

Abstract: A percussion drill bit for directional drilling tools. The drill bit comprises a head portion formed with an axially extending shank. The drill bit also comprises engagement means on the shank engageable with complementary engagement means formed on a drive chuck whereby rotational drive from the chuck may be transmitted to the shank. The head portion of the drill bit is formed with a plurality of slant faces arranged symmetrically about the head portion.